As summer ends, Toma desperately tries to catch up on homework—but that’s totally out of the question once a magician named Yamisaka kidnaps Index. As Toma tries to rescue his friend, he finds there may be more to her captor’s motives than just malice.

Therestina reluctantly provides Misaka with the clues she needs to find the group behind Febrie's secret. With Kongo's help, the girls identify Aritomi as the man they are pursuing, and find out more about him and his company, the STUDY Corporation.

As Toma and his group try to track down Oriana, they discover that a “Shorthand”—a specialized spell that operates on its own once being cast—is shorting out their magic. But before they can deactivate it, an incident happens at the middle school.

With the revelation that Febri is synthetic, Misaka is determined to find whoever built her, and have them fix her. The investigation is stalled on all fronts, even with the help of her friends running down leads, until help comes from a surprise source.

Eu, the most powerful necromancer in existence, slips into a pretty pink dress and picks up the most darling little chainsaw as she prepares to go all magical girl on a pesky demon with a plethora of lives!

As Yomikawa takes over investigating the runaway security robots, Konori invites the whole gang out to take in a bath at a bathhouse. On their way home, a number of detours lead them to a confrontation with yet another, much more dangerous runaway robot.

While under Circus's protection, a curious fact comes to light regarding Nai's true identity. With that clue in hand, Nai, Gareki, and several members of Circus pay a visit to where they believe Nai came from.

Febri takes an instant liking to Saten, and is warm to everyone except for Misaka, much to her chagrin. At Judgment, Uiharu is unable to find any information on who Febri is, so arrangements are made to admit her into an orphanage as a "Child Error."

The Roman Orthodox nuns continue their attack as Orsola risks everything to have Index decipher the Book of Law. The infamous grimoire could help them finally defeat their enemies—but that’s only if it works like it's supposed to.

Edasaki is due to be discharged from the hospital, and it is learned that she will be living with Haru'ue. The move is bittersweet for Uiharu, who is losing her roommate, but she feels it is for the best. Meanwhile, a new movement is afoot in the city.

Ayumu, Haruna, and Sera desperately search for Eu, but an evil zombie from the necromancer’s past is willing to kill to keep her by his undead side.

With the end of summer vacation approaching, the girls plan a study session at Saten's apartment to catch up on homework. Everyone is to bring an ingredient for a potluck stew party, but most have trouble deciding what to buy, leading to some surprises.

Dinner time is rudely interrupted by a mysterious female with an insatiable hunger for miso soup. Apparently, there is a war raging in the village of ninjas, and the curvy newcomer could use Eu’s help.

Misaka stands up for clone #10032, declaring that she is doing so because they are sisters. The next day, the two of them spend time in a park, where 10032 asks her for a special favor. Later, Misaka has difficulty trying to express her thanks to Kamijo.

Team Two is helping Team One put on their Circus parade and show, and Yogi gets Nai and Gareki to join the parade in an effort to cheer up Gareki. But a malfunctioning Team One rabbit throws a wrench into their festivities.

Kamijo races to the scene of the experiment, only to find that it has already started. Kamijo calls out Accelerator, who takes him to be yet another challenger to his position, until for the first time, as Misaka watches on, he gets his nose bloodied.